Cryogenic fluid piping systems, for example, for transport of liquified natural gas (LNG) or other cryogenic fluids, typically, employ vacuum-jacketed male and female bayonet connectors therein.
U.S. Pat. No. 4,515,397, issued May 7, 1985, shows a vacuum-insulated conduit. The conduit comprises an inside pipe and an outside pipe. A plate having a radially solid portion connects the end of the outer pipe to one end of a bellows, which is located around a portion of the inner pipe that extends beyond the end of the outer pipe. The opposite end of the bellows is connected to the outer circumference of the inner pipe. The space between the inside and outside pipe is evacuated to form a vacuum. Other U.S. patents relative to cryogenic systems include U.S. Pat. No. 4,011,732, issued Mar. 15, 1977, and U.S. Pat. No. 4,107,946, issued Aug. 22, 1978.
Failures within components of the fluid piping system can cause cryogenic material to leak from within the inside pipe into the vacuum area between the inner and outer pipes. Vaporization of leaked liquid cryogenic material and the cooling effects of the cryogenic material upon the outer pipe can create a situation where other parts of the pipe spool system may fail catastrophically. Additionally, leakage of cryogenic material from the inside pipe results in the loss of saleable product.
It is desirable to provide a new, improved, vacuum-jacketed, male-female bayonet connector particularly useful in cryogenic fluid piping systems, such as LNG systems, and which includes fail safe devices to minimize the leakage of cryogenic material during system malfunction and to avoid further catastrophic failure.
The invention relates to a male-female bayonet or pipe spool connector with a male bayonet with an expansion bellows and a cryogenic fluid piping system employing the connector as well as devices to minimize fluid loss and further catastrophic failure in situation where the system has failed.
A cryogenic fluid piping system is provided which comprises a plurality of two or more coupled first and second pipe spools. The first pipe spool has an outer pipe and a concentric inner pipe to carry cryogenic fluid, the outer pipe and inner pipe forming a vacuum-insulated connection. The first pipe spool also has a male bayonet at the one end of the first pipe spool which has an external male sealing surface, a first open end and other end, and an expansion-contraction peripheral bellows longitudinally about the external surface of the male bayonet adjacent the first open end. The first pipe spool also has a leak control ring circumscribing the inner pipe and situated between the expansion-contraction peripheral bellows and the male bayonet other end. The second pipe spool has an outer pipe and a concentric inner pipe to couple with the first pipe spool to carry cryogenic fluid in the coupled inner pipe and to form a coupled, vacuum-insulated connection. The second pipe spool also has a female bayonet having an internal, female sealing surface and a first open end and other end arranged and constructed to form a telescoped, zero tolerance, cryogenic vapor seal between the external surface of the male bayonet and the internal surface of the female bayonet for the stress movement of the bellows in the coupled use position. The system also includes a means to connect the opposing ends of the outer pipe of the first pipe spool and the second pipe spool.
The system additionally includes a pressure relief valve affixed to the outer pipe of the first spool for releasing cryogenic material which has leaked from the inner pipe of the first pipe spool.
The invention will be described for the purpose of illustration only in connection with certain illustrated embodiments; however, it is recognized that various changes, modifications, additions, and improvements may be made by those persons skilled in the art of the invention, as described and disclosed, without departing from the spirit and scope of the invention.